The use of electronic trip units within industrial-rated molded case circuit breakers allows a single circuit breaker design to be used over a wide range of circuit breaker ratings by means of a field-installable rating plug. An electronic trip unit is described in U.S. Pat. No. 4,589,052 and a rating plug is disclosed within U.S. Pat. No. 4,728,914.
U.S. Pat. No. 4,991,042 describes an electronic circuit breaker that includes a keypad and display on the circuit breaker cover for displaying stored trip parameters along with displaying the power systems voltage and current.
It would be economically advantageous to provide existing circuit breakers with metering facility without requiring the addition of a keypad and display.
Accordingly, one purpose of the invention is to describe a metering accessory that can be added to existing circuit interrupters employing an electronic trip unit without modification to the trip unit circuit.